The AI itself acts as a fun, though flawed writing assistant. Kind of like playing D&D with a very drunk but earnest DM.
However, Latitude (the company running AIDungeon) has serious privacy concerns (a massive data leak that they never disclosed to users nor commented on as well as reading private stories if they trip the filter for certain types of inappropriate content), and has shown a willingness to ignore feedback from their userbase, including deleting suggestions from their feedback site without warning or comment as to why.
All in all, this isn't a bad product (though Premium is overpriced), but Latitude as a company has lost my trust in them to handle users' privacy and respond to their users' feedback. Until they make clear action to improve security, privacy, and communication for their users, I cannot recommend their product.